A pretensioner commonly has a piston mounted in a tube which is mechanically or electrically activated to pretension the seat belt by winding in the belt spool a predetermined amount upon the detection of a predetermined deceleration rate of the vehicle, which indicates a crash situation. The piston may be connected to one end of an actuator cable, the other end of which is connected to the belt spool via a clutch mechanism. Thus when the piston is activated, the cable is retracted, and the clutch engaged so as to wind in the belt spool. This may be achieved for example by the cable being wound around an annular member mounted on the axle of the spool so as to surround the axle, which annular member decreases in diameter when the cable is tightened so as to grip the spool axle, such that the axle then rotates with the annular member to wind in the belt.
The tube carrying the piston normally has an outer cover and is mounted on an upper part of the clutch housing. Some applications require that the tube extend from the clutch housing at a different angle, for example in order to fit different vehicles. It is therefore necessary to provide clutch housings with different configurations. This necessitates the provision of a new clutch housing tool for manufacturing the housing. Usually, clutch housings are required in left hand and right hand versions, for use on opposite sides of a vehicle, adding further to the cost and inconvenience of providing different housings.